林惠嬌－河川指標污染物及水體分類水質標準之探討
The relationship between the River Quality Indicators and the Water Quality Classification Criteria
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河川水質特性，可以單一指標或綜合指標來表示。常用的單一指標有生化需氧量、溶氧、氨氮及懸浮固體等；綜合指標則以水質指數(Water Quality Index，WQI)、河川污染指數(River Pollution Index，RPI)及水體分類水質標準達成率等為臺灣地區常用以 評量河川水體品質及污染情形之綜合性指標。藉由指標污染物的篩選可以充分掌握水體特性，並分析影響河川水體分類水質標準達成率的主控水質指標項目，亦可應用於規劃河川污染削減措施之依據。
本研究以環保署河川水質資料庫為對象，分析各項水質參數對水質達成率之影響。分析結果顯示，基隆河之指標污染物為氨氮，於近五年中主控基隆河水質達成率之影響權數達百分之四十以上；南崁溪之指標污染物為氨氮及生化需氧量，主控南崁溪水質達成率之影響權數分別均達百分之三十六以上；高屏溪之指標污染物為氨氮及懸浮固體，主控高屏溪水質達成率之影響權數分別均達百分之三十以上。
本研究亦探討現行水體分類水質標準之適用性。現行標準中氨氮之水質標準僅有甲類及乙類的標準，丙類標準值同乙類，而丁、戊類則缺乏標準值參照，因此由指標污染物分析發現使氨氮為主控河川流域達成水體分類水質標準的主要影響因子。為更精確分類河川水質並更具表達水體用途之功能，爰提水體分類水質標準修正建議方案，修正後之水體分類水質標準能更經確的表達河川水質與水體用途之相關，並適度修正氨氮項目主控河川流域達成水體分類水質標準之影響程度，使水體分類水質標準達成率分析更合理。
The characteristics of river water quality can be representing either by a single or multiple indicators. Among the many indicators, BOD (Biochemical oxygen demand), DO (Dissolved oxygen), NH3-N (Nitrogen) and SS (Suspended solid) are most widely used as a single indicator in Taiwan.On the other hand, WQI (Water quality index), RPI (River pollution index) and achieve rate of water quality classification criteria are widely used as multiple indicator.
By choosing the appropriate indicator pollutants, the results can be used to represent the river water quality and to judge if the water quality classification criteria has been met. For example, the NH3-N concentration can be used as a indicator for Kee-Long River, and its value contributes more then forty percent of the achieve rate of water quality classification criteria. The concentrations of both the NH3-N and BOD concentration both can be used as indicators for Na-Kan River, where their values contribute more then thirty-six percent of the achieve rate of water quality classification criteria. The concentrations of both the NH3-N and SS can be used as indicators for Kuo-Pin River, where their values contribute more then thirty percent of the achieve rate of water quality classification criteria.
The suitability of the concentrations of NH3-N and BOD in water quality classification criteria were also discussed. For example, the NH3-N concentration criteria only regulated for Class A, B and C in current criteria. Under this strict criteria, the NH3-N was responsible for the low achieve rates for all of the three major rivers discussed in this study. Therefore, this study also discuss the reasonable criteria for NH3-N.